In packing technology, non-returnable packages of the can type are frequently used for the packaging of liquid, especially pressurized, contents such as beer, refreshing beverages and similar carbonated products. These known can packages generally consist of a cylindrical can body provided with a base, the upper end of the can body being closed with the help of a, substantially, planar end wall which is seamed onto the cylindrical can body. The cylindrical can body generally consists of plastic or metal, e.g. iron or aluminum, whereas the planar end wall as a rule always consists of sheet aluminum.
To make the package conveniently openable, the can is provided in most cases with some type of opening arrangement which on the one hand should make the package readily openable and on the other hand should allow a smooth emptying of the contents from the opened package.
A typical opening arrangement on such known can packages has a weakened or openable part in the planar end wall which by means of a pull-ring fixed to the weakened or openable part is adapted so that it can be completely pulled off to expose an emptying opening through which the contents of the package can be made accessible. One problem not infrequently encountered in this intrinsically simple and in most cases well-functioning opening arrangement is that the openable end wall has to be manufactured from a relatively soft material, preferably aluminium, which is both soft and easy to process, but which from a manufacturing point of view is a very energy-consuming and thus cost-demanding metal. In order to make the package more economical, therefore, it is necessary, among other things, to recover and reuse as much as possible of the aluminium content of the package. However the part of the end wall of the package pulled off during opening of the package, including the pull-ring, is thrown away in most cases and thus, is completely lost after a single use. Added to that is the concern that the wasted portion of the end wall represents a substantial environmental problem, since it can remain lying about in nature for a very long time before it breaks down through corrosion, and constitutes during this time, because of its sharp edges, a hazard to humans and animals.
Another opening arrangement on known can packages of the type described above consists of an opening incorporated in the end wall of the drum for emptying the contents which is covered by a cover strip or similar closure device detachably glued onto the outside of the end wall. This known opening arrangement is relatively simple and easy to manufacture and as a rule functions well, but it has the disadvantage, among other things, especially in the case of can packages for pressurized contents, that it requires environmentally doubtful and expensive glue to provide the joint between the cover strip and the package end wall with the required tightness and durability.